Linear decelerators and shock absorbers are commonly used to maintain or reduce the velocity or acceleration of an object or apparatus. These applications are typically utilized to control the speed or acceleration of an object so that the object may be more easily controlled or manipulated.
Linear decelerators and shock absorbers, which force fluid through a restricted orifice to convert the kinetic energy of the moving part into an increase of thermal energy of the fluid, are commonly used on machines. The smoothest deceleration of the moving parts is obtained by shock absorbers which offer a constant resistive force to the motion over the total length of the deceleration.
One class of such devices employs a piston connected to the moving object and movable within a metering cylinder or tube having a closed end. A series of spaced orifices are formed along the length of the tube wall, and the tube is supported within a housing filled with fluid. As the piston is forced into the tube by the motion of the moving part, the fluid is forced through the orifices, and the kinetic energy of the part is converted into thermal energy of the fluid. As the piston moves down the metering tube, it successfully closes off the orifices so that the force imposed on the load is maintained relatively constant, thereby resulting in a substantially linear deceleration of the moving part.
The force imparted on the object is a function of the effective configuration of the fluid orifices. Linear decelerators and shock absorbers of this class have been designed, wherein an outer tube or sleeve fits over the inner metering tube and is provided with metering means which coact with the metering orifices and inner tube to vary the resistive force in response to relative movement between the tubes, thereby allowing the linear decelerator to be selectively adjusted or used with parts having varying weights and kinetic energy.
Due to the intricacies of the orifices and fluid paths that must be created within such linear decelerators and shock absorbers, manufacturing such parts can be rather difficult and expensive. Typically, such parts are heat treated, ground, and commonly milled to provide the necessary configuration of the parts. Flats are commonly milled on cylindrical parts to allow for the flow of fluids between mating cylinders. Milling such flats during the last machining operation of the machining process may create raised burrs on precision ground parts. These burrs must be removed by a secondary operation, thereby creating added inefficiencies and inaccuracies in the manufacturing process. If the burrs are not removed, the burrs may become dislodged during the assembly and/or operation of the shock absorber. Such burrs may affect the relative sliding or rotation of adjacent parts, or the burrs may clog orifices, thereby affecting the performance of the shock absorber.
It would be desirable to design an adjustable shock absorber, whereby the milling of flats on substantially cylindrical parts was eliminated or minimized in order to increase the efficiency of the manufacturing of such parts.